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Viral suppression rates at delivery are higher among women who start antiretroviral (ARV) treatment for HIV after 20 weeks of gestation with a regimen based on Isentress (raltegravir) compared with those who take Sustiva (efavirenz)-based regimens, aidsmap reports.

Presenting their findings at the 2019 Conference on Retroviruses and Opportunistic Infections (CROI) in Seattle, researchers conducted a study of 408 pregnant women in South America, Africa, Thailand and the United States between 2013 and 2018. Half the study population started ARV treatment between 20 and 28 weeks of gestation while the other half began treatment between 28 and 37 weeks of gestation. The median gestational age at the study’s baseline was 29.6 weeks.

Fifty-three percent of the women were Latina and 36 percent were Black. Upon their entry into the study, the participants’ median viral load was about 8,000.

The women were randomized to begin ARV treatment with a regimen based on Isentress or Sustiva.

The researchers analyzed data on the 307 women whose HIV did not show signs of mutations that confer resistance to ARVs. Among these women, 94 percent of those in the Isentress group and 84 percent of those in the Sustiva group had a viral load below 200 at delivery. Among those who started ARVs after week 28 of gestation, a respective 93 percent and 71 percent of the women in each arm were virally suppressed. There was no such difference in the viral suppression rate among those women who started HIV treatment prior to week 28 of gestation.

Ninety-two percent of women in the Isentress group experienced either a 100-fold (99 percent) reduction in their viral load or a viral load below 200 after two weeks of treatment, had a sustained a viral load below 1,000 according to all tests taken after week four of the study and stayed on their assigned study drug through the point of their delivery. Sixty-four percent of those in the Sustiva group achieved these benchmarks of treatment success.

Ninety-three percent of those in the Isentress group and 69 percent of those in the Sustiva group experienced either a 100-fold viral load decline or a viral load below 200 within two weeks of treatment.

Women in the Isentress group developed a fully suppressed viral load after a median of eight days, compared with 15 days among the women in the Sustiva group.

Between the two study arms there were no differences in adverse health outcomes for the mothers or their infants, including cases of stillbirth, preterm birth or, among the mothers, grade 3 or 4 adverse health events. Six infants in the Sustiva group and one in the Isentress group had a positive HIV viral load following delivery. All of their mothers entered the study at week 28 of gestation or later.